Touch panel displays are known. See, for example, U.S. Pat. Nos. 7,436,393; 7,372,510; 7,215,331; 6,204,897; 6,177,918; 5,650,597, the entire contents of each of which is hereby incorporated herein by reference. Indeed, a number of different types of touch panel displays currently are available including, for example, resistive and capacitive touch panel displays.
In general, capacitive touch screens comprise a thin conductive film between a pair of glass layers. A narrow pattern of electrodes is placed between glass layers. The conductive film may be, for example, patterned indium tin oxide (ITO) or a thin wire mesh. An oscillator circuit, generally attached to each corner of the screen, induces a low voltage electric field in the coating. When the glass screen is touched, the properties of the electric field change. The touch screen's controller is configured to compute the coordinates of the point of contact with the screen by measuring the relative changes of the electric field at a plurality of electrodes.
Similarly, resistive touch screens generally comprise a substantially rigid substrate and a flexible cover, each having a surface coated with a transparent conductive material, usually of indium tin oxide (ITO). The substrate and cover are bonded together with the conductive surfaces facing each other but separated by an air gap produced by a pattern of transparent insulators deployed on one of the surfaces. When a user presses on the flexible cover, the cover is deformed and the conductive surfaces make contact. A controller is configured to measure the voltage drop in circuits resulting from contact between the conductive layers to determine the coordinates of the point at which the contact was made.
Resistive and capacitive touch sensitive systems typically are provided as transparent touch-sensitive panels that are placed in front of the screen or display surface of the underlying electronic display. For example, touch sensitive systems commonly are used in connection with several types of displays including, for example, cathode ray tubes (CRTs) and liquid crystal displays (LCDs).
FIG. 1 is a cross-sectional view of a conventional resistive touch-panel assembly 100. A glass substrate 102 is provided. For display sizes of 15″ in diagonal and larger, the glass substrate generally has a thickness of no less than 1.7 mm. In view of the above, it will be appreciated that one of the basic elements of a resistive or capacitive touch panel assembly is a glass substrate, coated with a first transparent conductive oxide layer 104, which typically is ITO. Additionally, the ITO coated glass substrate 102 is separated from another ITO coated article, e.g., via one or more spacers 106. The spacers 106 typically comprise a series of glass beads that often are substantially uniformly spaced apart, although other kinds of spacers sometimes may be used. Typically, this second ITO coated article is a flexible plastic film 108 such as, for example, polyethylene terephthalate (PET), which is coated with a second transparent conductive oxide layer 112 of ITO. The second transparent conductive oxide layer 112 is protected from the top with a hardcoat 110. The hardcoat 110 typically is provided as a substantially transparent layer that is both mechanically durable (e.g., is at least somewhat scratch resistant) and shows reduced markings when touched by a human hand. An LCD 114 or other suitable display device is provided “below” the glass substrate 102.
Although such touch panel displays have been made and have been commercially successful, further improvements are still possible. For example, the glass substrate used in such devices typically is expensive borosilicate, such as Corning glass. For many applications, the glass element of the touch-panel is reinforced by chemical treatment to increase tensile stress, which is a method alternative to thermal tempering of float soda-lime glass.
Additionally, the ITO layer typically is formed by sputter deposition in a reactive mode, e.g., when a metallic InSn target is bombarded by ionized argon in the presence of oxygen gas, thus coating the glass substrate with a substantially uniform and nearly stoichiometric ITO film. An alternative way to sputter indium tin oxide is to use a ceramic target, when the target is made of already stoichiometric ITO. In the latter case, the cost of the product is increased due to the higher cost of ceramic targets. However, the deposition rates of ITO in both cases, especially from ceramic targets, are known to be low, thus further increasing production costs.
Still further, to obtain a good quality of sputtered ITO, the substrate is normally heated during the deposition to 100-250 degrees C., which requires a special coater design.
Thus, it will be appreciated that there is a need in the art for techniques that improve the rates of the ITO coating for touch-panel displays. It also will be appreciated that there is a need in the art for making corresponding lower-cost ITO coated articles including a less expensive glass substrate, which may be heat strengthened or heat tempered. In any case, it will be appreciated that the techniques described herein may be used in connection with coated articles suitable for a wide variety of applications (e.g., other than touch panel display).
In certain example embodiments of this invention, a method of making a coated article is provided. A substantially transparent substrate is provided. A substantially sub-oxidized indium tin oxide (ITO) and/or metallic-mode indium-tin film is sputtered, directly or indirectly, on the substrate via an indium-tin (InSn) target. The sputtering is performed at or close to room temperature. The substrate together with the substantially sub-oxidized ITO and/or metallic-mode indium-tin film are heat treated such that the layer of substantially sub-oxidized ITO and/or metallic-mode indium-tin film is transformed into a substantially transparent and electrically conductive crystalline resultant ITO film.
In certain example embodiments, a method of making a coated article is provided. A substantially transparent soda-lime float glass substrate is provided, An intermediate film is sputtered, directly or indirectly, on the substrate via an indium-tin (InSn) target. The intermediate film comprises a substantially sub-oxidized indium tin oxide (ITO) and/or metallic-mode indium-tin film. The sputtering is performed at or close to room temperature. The substrate together with the intermediate film are heat strengthened or thermally tempered to produce an electrically conductive and crystalline resultant ITO film. The intermediate film comprises (InSn)xOy, with 0<y<0.5, and with x=1−y. The sputtering is performed in an environment having an oxygen-to-argon ratio of 0 to 0.4, more preferably 0 to 0.1.
In certain example embodiments, a method of making a touch panel display system is provided. A display panel (e.g., an LCD or other suitable display) is provided. A coated article comprising an ITO coating is provided, with the coated article having an intermediate film sputtered, directly or indirectly, on the substrate via an indium-tin (InSn) target. The intermediate film comprises a substantially sub-oxidized indium tin oxide (ITO) and/or metallic-mode indium-tin film. The sputtering is performed at or close to room temperature. The substrate and the intermediate film are heat treated to produce an electrically conductive and crystalline resultant ITO film. The intermediate film comprises (InSn)xOy, with 0<y<0.5, and with x=1−y. The sputtering is performed in an environment having an oxygen-to-argon ratio of 0 to 0.4, more preferably 0 to 0.1.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.